1. Field of the Invention
The present invention relates to a plasma display panel and, more particularly, to a plasma display panel that is capable of increasing an aperture ratio and facilitating alignment.
2. Description of the Background Art
In general, a plasma display panel (PDP) displays an image including a character or a graphic by allowing light to be emitted from a phosphor by a vacuum ultra violet (VUV) of 147 nm which is generated when a gas such as He+X3, N3+X3, H3+Ne+Xe is discharged. With its advantage of being easily thin and large, the PDP attracts much attention as a large-scale flat panel display.
FIGS. 1A and 1B show the structure of a 3-electrode alternating current (Ac) type PDP in accordance with a conventional art.
As illustrated, the PDP includes a lower glass substrate 1; an address electrode 2 formed on a certain portion of the lower glass substrate 1; a lower dielectric layer 9 formed at the entire surface of the lower glass substrate 1 and of the address electrode 2; a barrier rib 3 defined at a certain portion on the lower dielectric layer 9 to divide a plurality of discharging cells; a fluorescent layer 8 formed with a certain thickness on the barrier rib 3 and emitting visible rays of red, green and blue upon receiving an ultraviolet ray; an upper glass substrate 7; a scan electrode 6-1 and a sustain electrode 6-2 formed at a certain portion of the upper glass substrate 7 and intersecting the address electrode 2 in a vertical direction; an upper dielectric layer 5 formed at an entire surface of the scan electrode 6-1, the sustain electrode 6-2 and the upper glass substrate 2; and a passivation layer 4 formed on the upper dielectric layer 5 to protect it.
The scan electrode 6-1 consists of a transparent electrode 6-1A formed at a certain portion of the upper glass substrate 2; and a metal bus electrode 6-1B formed at a certain portion of the transparent electrode 6-1A.
The sustain electrode 6-2 consists of a transparent electrode 6-2A formed on a certain portion of the upper glass substrate 2; and a metal bus electrode 6-2B formed at a certain portion on the transparent electrode 6-2A.
The scan electrode 6-1 and the sustain electrode 6-2 are called a pair of sustain electrodes 6-1 and 6-2, and the metal bus electrodes 6-1B and 6-2B of the scan electrode 6-1 and the sustain electrode 6-2 are installed in a discharge space of one cell.
The operation of the conventional plasma display panel will now be described.
First, the upper glass substrate 7 and the lower glass substrate 1 are disposed in parallel with a certain space therebetween. A mixed gas is injected to a discharge space between the upper and lower glass substrate 1 and 7. When the mixed gas is discharged, the fluorescent layer 8 is coated on the barrier rib 3.
On the upper glass substrate 7, the upper dielectric layer 5 and the passivation layer 4 are sequentially stacked. The pair of sustain electrodes 6-1 and 6-2 consisting of the metal bus electrodes 6-1B and 6-2B and the transparent electrodes 6-1A and 6-2A are formed side by side between the upper glass substrate 7 and the upper dielectric layer 5 in a perpendicular direction to the address electrode 2.
The transparent electrodes 6-1A and 6-2A are formed on the upper glass substrate 7, and the metal bus electrodes 6-1B and 6-2B are formed on a certain portion of the transparent electrodes 6-1A and 6-2A.
The address electrode 2 is formed on the lower glass substrate 1, and the lower dielectric layer 9 is stacked at the entire surface of the lower glass layer 1 and the address electrode 2. The barrier ribs 3 are formed with the address electrode 2 therebetween on the lower dielectric layer 9.
The barrier rib 3 formed on the lower dielectric layer 9 cuts off an electric and optical interference between cells and is formed between the upper and lower glass substrates 1 and 7 to form a discharge space inside the cell.
The fluorescent layer 8 coated on the barrier rib 3 is excited by a vacuum ultraviolet with a short wavelength generated when a gas is discharged in the discharge space and generates three color visible rays. Accordingly, red, green and blue lights, three primary colors, are emitted from each cell.
The upper and lower dielectric layers 5 and 9 serve to store electric charges when the gas is discharged. The passivation layer 5 serves to protect the upper dielectric layer 5 against a sputtering phenomenon of plasma particles, and is mainly made of magnesium oxide (MgO).
Following the address discharge, discharge is sustained in the pair of sustain electrodes 6-1 and 6-2 as a voltage is applied thereto to cause the discharging. The transparent electrodes 6-1A and 6-2A of the pair of sustain electrodes 6-1 and 6-2 are made of a transparent conductive material with a light transmittance of above 90% (i.e., Indium-Tin-Oxide (ITO)) and pass through most of visible rays emitted from the fluorescent layer 8. However, in spite of the high light transmittance, such a substance as ITO has a low conductivity and thus has a very high resistance value, failing to efficiently transmit power. In order to solve this problem, the metal bus electrodes 6-1B and 6-2B made of a material with a high conductivity such as Ag or Cu are installed on the transparent electrode 6A. By doing that, the metal bus electrodes 6-1B and 6-2B lower down a resistance value of the pair of sustain electrodes 6-1 and 6-2 and prevent a voltage drop caused due to a high resistance of the transparent electrodes 6-1A and 6-2A.
The U.S. Pat. No. 5,838,106 registered on Nov. 17, 1998, the U.S. Pat. No. 6,242,859 registered on Jun. 5, 2001 and the U.S. Pat. No. 6,344,080 registered on Feb. 5, 2002 disclose plasma display panels and their fabrication methods.
However, the conventional PDP has a problem that since the metal bus electrodes 6-1B an 6-2B are formed at an upper portion of the discharge space of one cell, a portion of the visible ray emitted in the discharge space is interrupted, which deteriorates a luminance and efficiency of the PDP.
In addition, forming the metal bus electrodes 6-1B and 6-2B at the upper portion of the discharge space of one cell also causes a problem of reduction of an aperture ratio.